1. Field of the Invention
The present invention relates to an optical characteristic measuring apparatus and an optical characteristic measuring method, and particularly to an optical characteristic measuring apparatus and an optical characteristic measuring method capable of obtaining a film thickness and optical constants (refractive index n, extinction coefficient k) of a film formed on a substrate.
2. Description of the Background Art
When a semiconductor device or a flat panel display is manufactured, a plurality of films must be formed on a substrate. A reflection spectrometric film thickness meter disclosed in Japanese Patent Laying-Open No. 2000-65536 (PTL 1) is, for example, used to measure a film thickness and optical constants of the formed films. In the reflection spectrometric film thickness meter, light emitted from a white light source is reflected by a half mirror, and using a lens, a substrate is irradiated with the light. Furthermore, light reflected from the substrate is guided through the lens and the half mirror to a spectrometer, where the light is divided. Thereafter, a spectrum is detected by a detector that uses an image taking element such as CCD, and the detected spectrum is calculation processed. The film thickness and the optical constants of the films can thus be measured.
The film thickness and the optical constants of the formed films can also be measured using a spectroscopic ellipsometer disclosed in, for example, Japanese Patent Laying-Open No. 2004-138519 (PTL 2). In the spectroscopic ellipsometer, polarized light is emitted from a light source unit toward a substrate, and light reflected from the substrate is received by a light receiving unit to obtain a polarized spectrum of the reflected light. The film thickness and the optical constants of the formed films are thus measured.
Necessary information was, however, insufficient to obtain the only optical constants (refractive index n, extinction coefficient k) for a plurality of measuring points of the film, based only on the spectrum obtained by the spectrometric film thickness meter disclosed in PTL 1 or the spectroscopic ellipsometer disclosed in PTL 2. Therefore, the optical constants could not be obtained as the only value based on the obtained spectrum.